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"Ebot" is a project
of the Robotics Society of Southern California. The objective is to
provide a set of instructions to build a basic amateur robot. The
instructions are intended to be detailed enough to allow even an inexperienced
person to succeed. The goal of the project is to provide a fast route for our members
to build an operating robot.

The goal is to provide a discussion of the design decisions that
go into designing a robot like Ebot and to provide a specific design that the
members can build to; as well as enough information that the members can modify
the design if they wish.

The project will consist of a series of meetings just
before the monthly meeting of the RSSC. This meeting will generally review
progress of the builders since the last meeting, discuss the next stage of the
project, and provide builders with any necessary help or advice. Click
here for a project outline.

The mail list at http://groups.yahoo.com/group/sdrs-list
(San Diego Robotics Society, we share this list with them) will be used as a forum for discussion and
question/answers during the month between meetings.

The project will proceed in a logical manner to get the minimum
hardware constructed so that you can begin programming the Ebot. After
programming the initial tasks, various options will be presented to add more
capabilities to your Ebot.

Getting Started:

Platform base:
This is the plan for a basic round "platform", or chassis, on which
all the other components can be mounted.

Servo hack:
This section explains how to modify standard radio control servos to make them
rotate continuously, and hence be suitable for drive motors.

Wheels:
Tells how to attach model aircraft wheels to the modified servos above.

Servo mounting:
Gives various options on how to attach your completed motor/wheel assemblies to
the platform base.

Casters:
How to add skids or wheels to keep your two wheeled Ebot balanced.

Note: At this point you have installed all the parts
necessary to drive your Ebot around. Both in straight lines (more or less)
and turns. Next we'll add a microcontroller and a power supply, and
it will be ready to program and run.

Ready to run:

Microcontroller
Selection of the microcontroller that you will use on your Ebot is done
next. One reason to do this now is that the particular controller you
choose may affect the requirements for the power supply to be designed next.

Power Supply
A simple power supply to run the drive motors and the processor.

Note: You now have all the HARDWARE for a
basic robot. You just have to program it to do something useful.

Programming:

Note:This section will help you
to get your Ebot running under its own autonomous control. Most examples
will be for the Basic Stamp 2 microcontroller as that is what most of our club
members are doing. There will be some examples of the Motorola 68HC912B32
since that is what I'M using. You may find it interesting to compare the
two programming methods as they will be quite different.

Initial objective:
We established a simple task for the robot to accomplish that would require only
the ability to go straight forward for a specified distance, pivot 180 degrees
and return. This is designated as "Contest 1" when you follow
the link.

Note: Congratulations! You have now BUILT an operating
autonomous robot. Whle it is entirely possible that you are not very happy
with its performance in running Contest 1 (after all, the poor Ebot is asked to
do a job similar to you being asked to close your eyes, walk 10 feet
forward, turn around 180 degrees and walk 10 feet back)., we will now
start on a series of improvements which will make your Ebot much more capable
and accurate.

Adding Encoders:

This section , encoders,
will attempt to improve the
accuracy of your Ebot in running Contest 1 and any future navigational
tasks. An encoder is a device which measures how far each of the two drive
wheels has turned. Your microcontroller will then change the pulse widths
to the two motors to make them always have traveled the same distance.
This will cause it to go in a pretty straight line. Similarly, by
measuring how far each wheel travels when doing the 180 degree pivot, the Ebot
can aim back towards its starting point more accurately. After adding
encoders, Contest 1 should be pretty easy.

Distance
sensors permit your ebot to navigate with respect to other
objects. A common implementation is for your robot to navigate along
a wall and turn when another wall is reached. Wall following is another
approach to doing the second test/contest noted above.

PROGRAMMING: A quick
link to a list of all software available on this site.